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EARTHQUAKES    IN    CALIFORNIA,   (1888). 


By  Edward   S.    Holden. 


LIBRARY  OF  THE 

USIVEESHI 01  CALIf  OESIA. 

LICK  GBScRVATORY. 


[Feom  the  American  Journal  op  Science,  Vol.  XXXVTI,  Mat,  1 


Art.  XLI. — Earthquakes  in  California^  (1888) ; 
Edward  S.  Holden. 

In  1887  I  compiled  a  list  of  earthquakes  which  had  been 
recorded  in  California,  etc.,  from  1769  to  the  end  of  1887. 
This  was  printed  by  the  Regents  of  the  University  of  California 
in  a  pamphlet  of  78  pages  and  widely  distributed.  The  data 
there  given  have  been  discussed  in  two  papers  subsequently 
written.  The  first  is  a  note  on  Earthquake  Intensity  in  San 
Francisco  (1808-1888)  printed  in  this  Journal  for  June,  1888  ; 
aud  the  second  has  the  title  Earthquakes  in  California,  Wash- 
ington, and  Oregon  (1769-1888)  and  has  been  communicated 
to  the  California  Academy  of  Sciences.  These  three  publica- 
tions contain  all  the  data  which  I  have  been  able  to  collect, 
and  I  believe  that  no  deductions  of  especial  value  can  be  drawn 
from  the  data  except  those  which  are  there  given.  These 
statistics  could,  of  course,  be  tabulated  in  several  different  ways, 
but  it  is  my  opinion,  from  trials,  that  no  important  results  not 
already  given  would  follow. 

The  examination  of  past  records  has  naturally  led  to  the 
consideration  of  the  best  manner  of  making  future  ones.  The 
object  of  such  records  is  to  bring  to  light  all  the  general  facts 
as  to  distribution  of  earthquake  shocks,  as  to  topographic  areas, 
as  to  time,  as  to  average  intensity,  etc.,  and  also  to  enable  a 
study  to  be  made  of  particular  shocks, — as  to  velocity  of  transit, 
area  of  the  disturbed  region,  intensity,  etc.  In  order  to  study 
any  of  these  questions  with  profit  it  is  necessary  to  have  some 
kind  of  a  measure  of  the  intensity  of  each  earthquake  shock. 
The  most  satisfactory  instruments  which  I  have  seen  for  this 
purpose  are  those  invented  by  Professor  Ewing,  F.  R.  S.  These 
are  devised  on  sound  mechanical  principles  and  are  well  con- 
structed by  the  Cambridge  Scientific  Company. 

It  is  necessary  at  the  Lick  Observatory  to  keep  a  register  of 
all  earthquake  shocks  in  order  to  be  able  to  control  the  positions 
of  the  astronomical  instruments.  Accordingly  I  ordered  a  set 
of  Professor  Ewing's  instruments  for  the  Observatory,  which 
were  delivered  in  1887.  They  are  described  with  woodcuts  in 
Volume  1  of  the  Publications  of  the  Observatory,  (page  81) 


E.  S.  Holden — Earthquakes  in  California.  393 

and  in  the  Hand  Booh  of  the  Observatory,  (page  54).  The 
complete  set  of  instruments  will  give  for  each  shock  the  time 
of  its  beginning,  and  that  of  every  tremor ;  the  amplitude  of 
the  vibration  in  the  east  and  west,  the  north  and  south,  the  up 
and  down  directions  at  every  instant.  Such  a  complete  set  of 
instruments  requires  continual  attention  and  is  far  too  delicate 
and  troublesome  in  adjustment  for  general  use.  The  Duplex 
Seismometer  of  Professor  Ewing  seems,  however,  to  be  well 
suited  for  general  purposes.  It  gives  with  considerable  accu- 
racy, the  magnitude  of  the  earthquake  force  in  any  two 
directions  as  east  and  west  and  north  and  south.  The  vertical 
component  is  not  registered,  and  the  time  of  occurrence  must 
be  taken  from  a  watch.  Copies  of  this  instrument  can  be  had 
from  the  California  Electrical  Works  (35  Market  street,  San 
Francisco),  for  $15.  It  therefore  seems  to  be  a  suitable  pattern 
for  use  in  California,  and  elsewhere,  since  it  combines  compar- 
ative accuracy,  with  cheapness.  A  complete  set  of  Professor 
E wing's  instruments,  is  provided  as  I  have  said,  at  the  Lick 
Observatory.  The  duplex  seismometers  multiply  four  times  ; 
while  the  vertical  component  is  multiplied  ly^  times,  the 
horizontal  component  Z^-^  times  in  the  complete  instrument. 

Another  complete  set,  exactly  similar,  belongs  to  the  Univer- 
sity of  California,  at  Berkeley,  and  is  installed  at  the  Student's 
Observatory  there,  under  cJbarge  of  Professor  Soule.  This 
Observatory  also  has  a  Gray-Milne  seismometer,  complete. 
Copies  of  the  duplex  seismometer  are  set  up  also  at  the 
following  stations  : 

(1.)  San  Francisco,  near  Cliff  House,  residence  of  Hon.  A. 
Sutro. 

(2.)  San  Francisco,  917  Pine  street,  residence  of  Hon.  J.  R. 
Jarboe. 

(3.)  Chabot  Observatory,  Oakland,  in  charge  of  Mr.  Burck- 
h  alter. 

(4.)  Private  Observatory  of  Mr.  Blinn  in  East  Oakland. 

(5.)  Kono  Tayee,  Clear  Lake,  residence  of  Capt.  R.  S.  Floyd. 

(6.)  Observatory  of  University  of  the  Pacific,  San  Jose,  in 
charge  of  Professor  Higbie. 

(7.)  Students'  Observatory,  Berkeley,  in  charge  of  Professor 
Soule. 

(8.)  One  will  be  shortly  installed  at  Smith  Creek  Hotel,  at  the 
foot  of  Mt.  Hamilton. 

(9.)  Office  of  State  Weather  Bureau,  Carson,  Nevada,  in  charge 
of  Charles  Freund,  Esq. 

Copies  of  this  instrument  are  also  in  possession  of  Warner 
and  Swasey  of  Cleveland,  and  of  Capt.  C.  E.  Dutton,  of  the 
U.  S.  Geological  Survey  for  experiments.  I  believe  that  one 
will  be  shortly  mounted  at  the  Blue  Hill  Observatory,  near 


394  E.  S.  Holden— Earthquakes  in  California, 

Boston,  Massachusetts.  The  Lick  Observatory  also  possesses  a 
seismometer  invented  by  Professor  Milne  and  kindly  presented 
by  him,  which  is  designed  to  serve  for  general  purposes.  We 
have  not  thoroughly  tested  this  as  yet.  It  is  simple  in  construc- 
tion, and  inexpensive.  A  description  of  it  may  be  found  in 
Trans.  Seis.  Soc.  of  Japan,  vol.  xii. 

The  instruments  above  named  which  are  in  California  have 
been  visited  and  adjusted  by  Mr.  Keeler  of  the  Observatory 
(who  is  in  charge  of  our  earthquake  instruments),  and  the 
owners  of  these  instruments  have  kindly  reported  the  occur- 
rence of  shocks,  and  have  often  sent  blue  prints  or  tracings  of 
the  records  made.  The  reports  of  Mr  Jarboe,  Mr.  Blinn,  and 
Mr.  Burckhalter  have  been  especially  full,  as  will  be  seen  from 
what  follows.  Wm.  Irelan,  Esq.,  Dr.  J.  B.  Trembley  of  Oak- 
land, and  U.  S.  Surveyor  General  Irish  of  ]Mevada,  have  kindly 
taken  the  pains  to  send  accounts  of  all  shocks. 

I  have  also  copied  from  such  newspapers  as  fell  under  my  eye 
all  data  respecting  California  earthquakes.  These  are  given 
in  what  follows,  together  with  the  results  obtained  from  the 
various  instruments.  To  make  this  record  complete  the  reports 
of  the  U.  S.  Light  House  Board,  of  the  U.  S.  Geological 
Survey,  and  the  annual  records  of  earthquakes  given  by 
Professor  Pockwood  in  this  Journal  should  be  consulted.  As 
these  are  available  to  all,  I  have  not  reprinted  any  data  from 
them.  It  is  intended  in  future  years  to  continue  such  records 
as  the  present  one.  The  extremely  local  character  of  some  of 
these  shocks  is  noteworthy. 

Earthquakes  in  California,  1888. 

1888,  January  7,  10:25  P.  M.— S.  F.  (II) :  Berkeley  (lY),— 
at  Berkeley  a  loud  explosion. — Professor  Kellogg. 

January  18,  at  night. — Berkeley,  a  slight  shock  (N.E.-S.W.) 
recorded  on  duplex  seismometer  (I?  II?  III?). — Professor 
Soule. 

Jam^uary  16,  11:39  P.  M. — S.  F.:  single,  short,  sharp  shock 
(lY). — E.  S.  H.  (I  have  no  other  report  of  this,  and  it  must 
therefore  be  regarded  as  doubtful.) 

January  17,  10:10  P.  M.— S.  F.~E.  E.  Barnard.  Oakland, 
from  N.E.  to  S.W.  (III?  lY ?).— Prof essor  Edwards. 

January  26,  ? — Healdsburg,  10  sec.  duration,  S.  F.  Chronicle, 
Jan.  28.     (Total  eclipse  of  the  moon  on  January  28.) 

January  29,  10:35  P.  M. — Carson,  Nevada,  a  slight  shock 
(lY  to  Y)  Grass  Yalley,  CaL:  the  same  shock;  (II). — Grass 
Yalley  Tidings,  Feb  3. 

Jam^uary  30,  4:15  A.  m. — S.  F.  [not  reported  in  newspapers]. 

J.  R.  J. 


E.  S*  Holden — Earthquakes  in  California.  395 

February  18,  2:50  a.  m. — Fort  Bragg  :  three  severe  shocks^ 
(Y  V) ;  the  first  at  2:50,  the  other  at  intervals  of  one  or  two 
minutes.  Mendocino :  three  shocks ;  the  first  at  2:55,  the 
others  at  intervals  of  three  or  four  minutes. — (S.  F.  Bulletin^ 
February  18.) 

Eehniary  ?  about  4  A.  M. — Menlo  Park  :  sleepers  waked  (Y 
or  YI).~J.  T.  Doyle,  Esq. 

February  29,  2:51  p.  m. — S.  F.:  on  Montgomery  street,  peo- 
ple alarmed  (Y) ;  Pine  and  Mason  streets,  more  severe,  (YI) ; 
Washington  and  Mason  streets,  (YI).  Two  waves  on  duplex 
seismometer  (917  Pine  street.).     The  motion  of  the  earth  was 

«._K  68°  W.  to  S.  68°  E.      l—^.  56°  E.  to  K  66°  W. 
The  shock  h  was  most  severe. 

Berkeley  :  not  felt,  not  registered. — Oakland  :  (II.) — Bel- 
mont :  not  felt— San  Eafael :  (lY  or  Y)  2:48  p.  m.,  E.  to  W.— 
Santa  Posa :  2:55  p.  M.,  violent ;  people  ran  out  of  houses, 
(YI). — Petaluma :  2:55  p.  m.,  walls  cracked  (YII)  sound  of  an 
explosion  heard.  The  severest  for  many  years.— Healdsburg  : 
2:44  p.  M.,  light  K  to  S. — Martinez  :  2:45  P.  M.,  two  shocks  one 
minute  apart  (YI). — S.  F.  Alta^  Chronicle,  Bulletin^  Feb. 
29th  and  Mar.  1. 

March  7,  7:54  A.  M. — Pasadena  :  7:58  A.  M.,  (YI) ;  from 
N.W.  to  S.E.,  duration  three  seconds. — Los  Angeles  :  a  little 
after  8  A.  M.  (YI)?  "severest  for  18  years;  no  damage  to 
buildings,"  no  very  heavy  articles  overturned  (YI).  [S^ote  : 
on  1883,  Sept.  5th,  a  shock  (YI)  was  felt  at  Los  i\ngeles, 
E.  S.  H.J — San  Diego  :  scarcely  felt  (11).  (Pasadena  Daily 
Star ;  also  S.  F.  Alta,  Chronicle,  Mar.  7,  8). 

March  28,  1:41  A.  M. — S.  F.:  slight  shock,  but  sufficient  to 
awaken  a  sleeper  (Y).  Direction  of  shock  nearly  ]^.  and  S., 
on  duplex  seismometer,  917  Pine  street.  Professor  Davidson 
says  duration  f  second,  and  shock  from  W.  to  E. — S.  F. 
Bulletin,  Mar.  29. 

April  9,  7:50  A.  M.— Kiverside :  slight  shock  (lY)  KE.  and 
S.W.     (S.  F.  Bulletin,  April  9,  Chronicle,  April  10.) 

April  12,  about  5:15  A.  m. — Riverside :  the  shock  sufficient 
to  waken  sleepers  (YI)  with  loud  noises  accompanying.  Col- 
ton,  5:30  A.  M.     (S.  F.  Chronicle,  April  13.) 

April  28,  [8:45  P.  M.] — On  the  Lick  Observatory  seismo- 
graph an  earthquake  record  was  found  April  29.  From  the 
trace  of  this  shock  the  following  data  are  taken.  The  dimen- 
sions given  below  are  to  be  divided  by  3*3  for  the  Horizontal 
and  by  1*6  for  the  Yertical  components,  to  get  the  actual  earth 
movements.  The  times  are  given  in  seconds  after  a  zero 
epoch  arbitrarily  assumed.  The  pen  which  marks  the  W.  and 
E.  components  registered  a  line  y*-^-  of  a  millimeter  wide 
throughout.     There  appear  to  be  widenings  of   this  line  as 


396  E.  S.  Holden — Earthquakes  in  California, 

early  as  fifteen  seconds  before  the  zero  second  adopted,  but 
the  amplitude  of  E.  and  W.  tremors  is  never  more  than  -^ 
of  a  millimeter  during  the  whole  shock  and  the  time  of  their 
beginning  cannot  be  fixed.  I  presume  we  have  here  a  case 
where  the  normal  vibrations  were  strictly  in  an  E.  and  W. 
plane.  The  transverse  vibrations  which  arrived  later  are  there- 
fore N.  and  S.  and  of  their  full  size  in  the  diagram.  We  may 
then  dismiss  all  further  consideration  of  the  E.  and  W.  wave. 
It  had  scarcely  a  measurable  amplitude.  At  0  seconds  the  N. 
and  S.  tremors  begin  to  show ;  the  whole  record  of  the  vertical 
component  is  lost  till  17  seconds. 


3  sec.  th 

e  earth  m 

oved  S.  of  t 

he  neutral 

line  V 

5 

N. 

({ 

6 

S. 

« 

9 

S. 

(( 

10 

N. 

(( 

Hi 

S. 

(( 

13 

N. 

(C 

15 

S. 

C( 

4 

16 

N. 

(C 

18 

S. 

<( 

j 

V.) 

N. 

(C 

* 

and  small  tremors  with  a  double  amplitude  of  about  \^^  (on 
the  trace)  continue  till  ^^  seconds. 

The  vertical  component  as  recorded  by  the  machine  is  given 
below : 

At  18  sec.  the  earth  moved  above  the  neutral  line  l""™ 
19  "  below  "  i 

21i  "  above  "  | 

23  "  below  "  1 

and  tremors  of  not  more  than  J""™  continue  on  the  trace  till 
about  56  seconds. 

We  may  assume  for  a  basis  of  computation  : 

Number  of  waves  in  10  seconds  =4, 
Period,  about  2*5  seconds  =:T, 
Amplitude  magnified,  l""™,  a=0-3"^™, 

Velocity  of  projection  =V=-7-^  =  0*75, 

Intensity  = — =1-90, 

which  corresponds  to  about  I  on  the  Eossi-Forel  scale.     The 
period  of  these  waves  is  very  slow. 

April  28,  8:48  p.  m. — Reno  (Nevada),  a  smart  shock :  three 
waves  in  3  sec,  followed  by  a  general  trembling  for  10  sec. 


E.  jS,  Holden — Earthquakes  in  California,  397 

The  time  of  tlie  third  and.  severest  shock  was  8  h.  48  m.  38  s. 
p.  M.  Direction  S.  to  N.  (letter  from  U.  S.  Surveyor  General 
Irish).  Two  other  observers  say  W.  to  E. — Grass  Valley  :  felt 
in  the  Idaho  mine  below  the  1600  ft.  level,  Alta,  May  2d. 
Yery  heavy,  lasting  5  sec,  from  E.  to  W.  {Chronicle^  April  30). 
— Grass  Yalley  :  the  Orleans  mine  was  flooded.  The  shock 
was  at  8:45  p.  M.  and  very  heavy  (YII).  It  was  preceded  by 
a  loud  noise.  The  duration  was  about  5  sec,  and  the  wave 
was  E.  to  W.  Clocks  stopped,  plastering  fell,  and  also  tops  of 
chimneys. — IN'evada  City :  walls  of  courthouse  cracked  (YIII). 
— At  Marysville,  Downieville,  Truckee,  Colfax  and  Sacramento 
the  shock  was  very  strong  (G.  Y.  Tidings^  April  30,  May  2). — 
Nevada  City :  two  severe  shocks  at  8:48  P.  M.  preceded  by  a 
deep  rumbling  sound.  Direction  N. — Dutch  Flat ;  8:46  P.  M., 
severe  from  S.  to  N.  People  were  badly  frightened. — Stock- 
ton :  four  shocks  at  8:40,  from  K.  to  S. — Dixon,  8:45  P.  M. — 
Biggs :  heavy  shock  "  lasting  75  (?)  seconds "  [seven  to  ^nq,  ? 
E.  S.  H.],  at  8:45  (YII)  plastering  cracked,  etc. — Santa  Eosa: 
slight  shock  at  8:45,  N.  and  S.  (III).— Truckee :  8:47,  duration 
two  seconds,  (S.  E.  Examiner^  April  29). — Oroville :  8:45  P.  M. 
Short,  quick  shock. — S.  F. :  barely  perceptible  in  third  story 
of  917  Pine  street.  No  record  on  duplex  seismometer  in 
basement  (I). 

April  30,  about  4  a.  m. — Grass  Yalley :  Tidings^  April  30. 
—Downieville :  3:40  A.  M.  two  light  shocks  (lY),  (S.  F.  Bul- 
letin^ April  30). 

May  4,  1:55  P.  M. — S.  F.,  917  Pine  street,  decided  shock, 
not  registered  on  duplex  seismometer,  J.  K.  J. — S.  F.,  slight 
shock  (II)  of  a  few  seconds  duration,  {Bulletin^  May  4). 

May  6,  9  h.  42  m.  22  s.  P.  M.  (E.  S.  H.).— Lick  Observatory : 
sadden  shock  (III)  E.  S.  H.,  preceded  by  a  rumbling  noise 
(PoRCHEE.)  (Registered  on  duplex  seismometer). 

July  11,  at  night. — Susan ville:  slight  shock  (lY??),  S.  F. 
Bulletin.^  Jul.y  IS- 

August  14,*  9:57  a.  m.— S.  F.,  917  Pine  st.  Intensity  (II)  on 
P.  F.  scale.  The  duplex  seismometer  gives  a  looped  trace  on 
the  plate  (magnified  four  times)  7°""  N.K.E.  to  S.S.W.  (direc- 
tion of  first  shock),  4™""  at  right  angles  to  this.  The  motion 
of  the  earth  was  therefore  S.S.W.  to  N.N.E. — Lick  Observa- 
tory :  direction  on  the  plate  KK.E.,  of  the  earth  S.S.W.  The 
trace  is  a  wavy  line  (magnified  four  times)  8'°°'  long.  JST.^.E. 
and  S.S.W.  with  six  waves  1™™  high  at  right  angles  to  this. 
Probably  the  shock  was  nearly  vertical  here. 

September  10, 1:53  a.  m.— S.  F.,  917  Pine  street:  slight  shock 
(II)  not  registered  on  duplex  seismometer,  J.  R  J. — Oakland: 
slight  shock,  C.  Burckhalter.  Three  shocks  at  1:50  a.  m.  in 
quick  succession,  attended  by  noise;  windows  did  not  rattle 


398  E.  S.  Rolden — Earthquakes  in  California, 

(III?),  Dr.  Trembley.  It  waked  sleepers  in  Oakland  (V?),  E. 
Booth. — Berkeley ;  slight. 

September  15? — Lick  Observatory:  the  seismograph  started 
at  6:15  A.  m.,  but  as  the  record  was  not  like  that  of  a  shock, 
Mr.  Keeler  (in  charge  of  the  instrument)  supposes  the  tremor 
which  started  the  instrument  to  have  been  due  to  a  high  wind. 

Septeniber  17,  3:51  A.  M. — Lick  Observatory :  The  seismo- 
graph gives  the  following  records  (magnified  1'6  times  for  the 
vertical,  3*3  times  for  the  horizontal  components).  At  3 
seconds  after  an  assumed  zero  second,  the  vertical  component 
began  its  trace  with  a  wave  of  period  about  1^  seconds.  The 
amplitude  (on  the  trace)  is  hard  to  estimate  but  is  probably  not 
less  than  6"""  for  the  first  semi- wave,  then  about  1"™  for  a  full 
wave,  and  after  this  mere  tremors  until  about  40  seconds.  The 
N.  and  S.  component  (magnified)  was  as  follows: 

At  4*3  seconds  the  earth  moved  S.  of  the  neutral  line  5™" 

5-7  " 

5-9  " 

6-1  « 

6*4  " 

6-9  " 

7-6  " 

8-9  « 

and  tremors  occasionally  as  large  as  J™""  continued  until  about 
40  seconds. 

The  E.  and  W.  component  (magnified)  was  as  follows : 
At  4*3  seconds  there  was  strong  movement  of  the  earth  west 
of  about  3"™°' ;  this  was  followed  by  a  wave  of  period  about  1 
second  double  amplitude  2™™ ;  and  this  again  by  another  of 
period  J  second  double  amplitude  l""".  After  this  tremors 
continue  for  about  30  seconds. 

The  strata  of  which  Mt.  Hamilton  is  composed  lie  at  a  high 
angle  to  the  horizon  and  the  direction  of  the  stratification  is 
nearer  N.  and  S.  than  E.  and  W.  The  earthquake  instruments 
are  at  the  very  summit  of  the  mountain.  This  may  account 
for  the  fact  that  (at  least  for  the  shocks  so  far  observed)  the 
vertical  component  is  relatively  large,  and  that  the  N.  and  S. 
component  (in  the  general  direction  of  the  stratification)  is 
usually  far  larger  than  the  E.  and  W.  component.  The  record 
of  this  shock  on  the  duplex  seismometer  is  very  interesting, 
but  it  gives  no  information  additional  to  the  above. 

'We  may  then  assume  as  a  basis  of  computation  for  this 
shock  : 

Number  of  waves  in  10  seconds  =6  or  7,  say  6|. 
Period,  T,  of  the  representative  wave  =0*5  sec. 
Amplitude  of  the  representative  wave  (magnified)  =2-5™™ 
a  =  O-S"^™. 


N. 

u 

2 

on  to 

u 



N. 

u 

2i 

S. 

(( 

H 

N. 

(( 

1 

S. 

(( 

li 

IsT. 

(( 

.     14 

E.  8.  Holden — Earthquakes  in  California.  399 

Velocity  of  projection  =^^7|^=10'0. 

Intensity  =  —  =  126. 

This  corresponds  approximately  to  Y-YI  on  the  Rossi-Forel 
jcale,  according  to  the  table  in  this  Journal,  June,  1888,  p.  429, 
ivhich  was  derived  from  Japanese  shocks. 

Chabot  Observatory :  the  time  of  the  shock  is  8  h.  50  m. 
dIus  or  minus  one-quarter  of  a  minute  (W.  Irelan,  Esq.).  It  is 
registered  on  the  duplex  seismometer  plate  as  follows.  The 
first  motion  (of  the  pen,  magnified  four  times)  is  2°"°^  to  the  W., 
then  follow  several  small  tremors  towards  the  S.E.  The  mo- 
tion of  the  earth  is  of  course  in  the  reverse  directions. — Lick 
Observatory,  3:51  A.  M. :  severe  shock,  lasting  several  seconds. 
Strong  vertical  component  (YI  to  Yll)  observed  by  E.  S.  H. 
Also  on  L.  O.  seismometer. — ^Gilroy,  sharp  shock :  Santa  Cruz, 
heavy,  (S.  F.  Call,  Sept.  18).— S.  R,  917  Pine  street:  very 
slight,  no  record  on  seismometer,  J.  R.  J. 

September  23,  about  11:30  A.  M. — S.  F.,  917  Pine  street : 
very  slight  shock,  J.  R.  J. 

Octoler  3,  12:52  P.  M.— San  Miguel,  S.  L.  O.  Co.:  light 
shock,  2  sec.  duration,  N.  to  S.  (III).  Another  at  same  place 
at  1:02  P.  M.,  quite  severe,  IS",  to  S.,  4  sec.  duration,  no  damage 
done  (YI  ?),  S.  F.  Chronicle,  Oct.  4. 

October  4,  P.  m. — Paso  Robles  :  slight  shock. — S.  F.  Report, 
October  5. 

October  4,  11  P.  M. — San  Diego. — S.  F.  Bulletin,  October  5. 

October  5,  4h.  41m.  30s. ±  10s.  A.  M — Chabot  Observatory: 
the  shock  was  sufficient  to  waken  a  sound  sleeper  (YI).  On 
the  duplex  seismometer  plate  the  trace  begins  with  a  tremu- 
lous motion  toward  the  W.,  followed  by  two  sharp  jerks  to  the 
S.  The  motion  of  the  earth  is  contrary  to  the  motion  of  the 
plate. 

October  23  ? — Lick  Observatory  :  During  Mr.  Keeler's  ab- 
sence the  earthquake  instruments  were  in  charge  of  Mr.  Hill. 
On  October  23,  at  6  P.  M.,  I  noticed  that  the  earthquake  instru- 
ments were  in  their  usual  state.  I  also  noted  at  9  P.  M.,  October 
24,  that  a  shock  had  occurred  previously.  The  clock  dial  of 
the  earthquake  clock  is  divided  to  12  hours  (instead  of  to  24 
hours  as  it  should  have  been),  and  there  is  an  ambiguity  of  12 
hours  in  the  time  of  the  shock,  which  is  either 

October  23,  llh.  42m.  p.  M.,  or  October  24,  llh.  42m.  A.  M.— 
The  shock  was  sufficient  to  start  the  clock  of  the  Ewing 
seismograph,  but  the  plate  did  not  move.  The  duplex 
seismometer  plate  shows  a  tremulous  wave  in  the  direction 
N.E.  and  S.W. 


400  E.  S.  Holden — Earthquakes  in  California. 

October  24,  2:50  a.  m.— East  Oakland  :  (Y)  Mr.  Blinn's 
Observatory.  The  duplex  seismometer  plate  shows  a  trace 
from  S.  to  N.  in  general  direction.  The  first  trace  on  the 
plate  is  that  of  a  single  wave  about  2m.  in  amplitude 
(magnified  four  times)  followed  by  small  tremors. — Chabot 
Observatory  :  the  plate  of  the  duplex  seismometer  shows  the 
first  wave  strongly  towards  the  N.E.  The  trace  of  this  wave 
(magnified  four  times)  is  a  straight  line  O""""  long.  This  is 
followed  by  two  waves  of  the  earth  as  it  regained  its  original 
position.  The  motion  of  the  earth  is  contrary  to  that  of  the 
pen  on  the  plate. 

October  25,  in  the  night. — Mr.  Blinn's  Observatory.  The 
duplex  seismometer  gives  a  tremor,  and  the  general  direction 
of  the  trace  on  the  plate  is  S.E.  to  N.W. 

November  4,  3:36  A.  M.— Lick  Observatory  (YI).— E.  S.  H. 
Mr.  Barnard  gives  the  time  as  3h.  37im.,  plus  or  minus  -J  m. 
The  duplex  seismometer  gives  a  very  complex  knot  of  curves 
ending  by  a  trace  on  the  plate  towards  the  S.W.  The  trace  on 
the  Milne  seismometer  (in  cellar  of  the  Meridian  Circle  House) 
cannot  be  interpreted,  as  the  instrument  had  just  been  set  up 
and  probably  was  not  adjusted  properly. 

November  18,  2:28  P.  M. — S.  E.,  917  Pine  street :  two  shocks 
north  and  south  (YII)  registered  on  seismometer.  Another 
light  shock  at  5:38  P.  M. — J.  E.  J. — San  Eafael :  2:30  p.  M., 
'^.  and  S.— Oakland  :  2:29  P.  M.;  one  chimney  fell  (YII?).— 
Berkeley:  2:28  P.  M.;  duration  7  sec;  a  third  shock  at  5:35 
P.  M.     (S.  F.  Examiner^  Nov.  19.) 

Lick  Observatory :  not  felt,  not  registered. — Chabot  Obser- 
vatory :  2h.  27m.  53s.,  very  sharp  shock ;  3:30,  slight ;  5h. 
37m.  20s.,  sharper  than  the  second  shock.  The  duration  was 
3  sec.  The  trace  on  the  duplex  seismometer  is  a  very  com- 
plicated circular  knot  of  5  to  6""°  diameter  (magnified  four 
times)  with  a  looped  excursion  of  the  pen  toward  the  east 
gram  fi-Q^n  the  center  of  the  knot,  and  another  straight  one 
from  the  center  to  the  W.S.W  ,  also  of  6™™.  All  three  shocks 
are  on  this  single  plate. — In  Oakland  no  real  damage  was  done. 
Two  or  three  chimneys  were  overthrown  and  panes  of  glass 
were  broken  (YI,  or  YII  ?).— East  Oakland  :  2:29  P.  M.,  N.  to 
S.,  duration  2  sec;  3:45  p.  M.,  very  light ;  5:36  P.  M.,  E.  to  W., 
duration  2  sec — (S.  E,  Bulletin,  ISTov.  19). — Napa :  2:36  P.  M., 
duration  10  sec. — S.  F.  Chronicle,  Nov.  19. — Haywards,  San 
Leandro,  Niles  :  not  felt. — Mr.  Burckhalter. — Clear  Lake  :  not 
felt.— Capt.  K.  S.  Floyd. 

It  is  also  reported  by  Capt.  Edmundson  of  the  ship  "  Drum- 
lanrig,"  that  he  found  soundings  of  35  fathoms,  35  miles  S.W. 
of  the  Farallones  where  no  shoal  is  now  known  to  exist.  This 
point  will  be   determined  by  the   proper   authorities.     It   is 


E.  S.  Holden — Earthquakes  in  California.  401 

supposed  by  some  that  the  shock  of  N'ov.  18  may  have  pro- 
duced this  shoal  which  is  not  down  on  the  charts. 

East  Oakland  :  Mr.  Blinn's  Observatory.  The  first  shock 
was  severe  (VI)  lasting  about  two  seconds.  The  time  was  very 
approximately  2h.  27m.  57s.  (Blinn).  Mr.  Irelan  gives  2h. 
27m.  54s.  Trees  and  hedges  were  seen  to  move.  A  few  light 
articles  were  overthrown,  pictures  were  displaced,  a  clock  was 
stopped,  (its  pendulum  was  in  the  plane  N.E.  and  S.W.);  5 
chimneys  were  thrown  down  on  23d  avenue  ;  a  noise  was  heard 
after  the  first  shock.  The  second  shock  was  (II)  at  3:48  P.  M. 
The  duplex  seismometer  trace  is  a  loop  about  l""""  in  diameter. 
The  third  shock  was  (III)  at  5h.  38m.  45s.  P.  M.  The  trace  on 
the  duplex  seismometer  begins  in  an  ellipse  2°""  E.  and  W., 
1™°^  ]^.  and  S.,  and  then  there  is  a  confused  record  of  tremb- 
ling 3°^°^  :N".W.  and  S.E.  by  X^"^"^  at  right  angles  to  this. 

Decemher  11,  3:29  P.  M. — Lick  Observatory  :  the  shock  was 
sudden  and  (lY)  in  intensity.  Time  by  watch  3h.  28m.  59s.  ; 
by  earthquake  clock  3h.  29Jm. — J.  E.  K.  A  humming  noise 
was  heard  after  the  shocks.  There  were  two  such  at  an 
interval  of  2  sec.  The  time  of  the  last  was  8h.  28m.  58s.  plus 
or  minus  3  sec— E.  E.  B.     Intensity  (Y),  time  3:28.8.— E.  S.  H. 

The  duplex  seismometer  gives  a  record  (magnified)  begin- 
ning with  a  sharp  straight  trace  to  the  N.W.  3°"™  long,  then  a 
straight  trace  to  the  N.E.  If  ""^  long,  then  a  straight  trace  to 
the  N.W.  nearly  2"™  long,  and  at  the  end  of  this  the  pen 
has  recorded  a  confused  tremor  in  a  space  about  1™™  square. 
The  record  of  the  Ewing  seismograph  is  as  follows  :  (The 
adjustment  of  the  marking  pen  for  seconds  has  been  changed 
so  that  there  are  95  beats  of  the  pen  to  I  min.  of  time.) 

There  are  very  slight  ^vertical  tremors  for  the  first  three 
beats  ;  they  then  vanish  completely.  Their  period  is  from  -J- 
to  ^  of  a  second  of  time  ;  their  double  amplitude  is  not  above 
-j^  of  a  millimeter. 

The  east  and  west  vibrations  last  only  for  two  beats  though 
the  faintest  perceptible  tremor  lasts  until  the  twentieth  beat 
after  the  beginning.  Their  greatest  double  amplitude  is  not 
above  ^  a  millimeter,  and  their  period  appears  to  be  about  -J  a 
second. 

The  north  and  south  vibrations  are  well  marked.  From  the 
zero  beat  (beginning)  until  IJ  beats  there  are  marked  tremors. 
From  IJ  beats  to  4f  beats  vibrations  having  a  double  amplitude 
of  about  one- half  a  millimeter,  and  a  period  of  about  -J  to  J  of 
a  second  time.  At  the  end  of  the  6th  beat  the  marked  tremors 
cease  and  a  very  faint  tremor  continues  to  the  end  of  the  20th 
beat,  and  possibly  to  the  end  of  the  33d  beat.  As  a  basis  of 
computation  we  may  assume  from  the  record  of  the  north  and 
south  component : 


402  E.  S.  Holden — Ea/rthquakes  in  California. 

Double  amplitude  magnified  3-3  times  =0*5"''^. 

a— D'OS™"". 

T  =0-3  seconds. 

v  =  -—-=\'1.  1= — =36. 

T  a 

This  corresponds  to  about  II  on  the  R.-F.  scale  according  to 
the  paper  frequently  cited  above.  The  intensity  was,  however, 
lY  or  higher. 


THE  UNIVERSITY  LIBRARY 

UNIVERSITY  OF  CALIFORNIA,   SANTA  CRUZ 

SCIENCE  LIBRARY 

This  book  Is  due  on  the  last  DATE  stamped  below. 

AUG  1  5  1383  REC'D 


MAY  2  8  1984 

to?    1983  RECb 


Series  2477 


uc-SAffTA  cauz 


3  2106  0053^ 


m 


